Digital camera folks have it easy when it comes to taking a picture and then using it. Those of us who still use film have more work to do. While I'm not going to prove today that film still surpasses computer chips and CCD's in detail and tonal recording, I will assert that in today's photography even classic film shooters need to rely on a conversion to a digital image in order to effectively manage images. That conversion process is the subject here.
In my experience the choice of equipment is directly related to the successful transformation of film to digital image. Just like a photographer is going to choose the best equipment available, cutting corners on a scanning device will only ruin an otherwise great image on film. To that end, flat bed scanners should be removed from the equation. Using an 8 1/2 inch by 14 inch scanning bed for a 35mm negative is losing quality. Imagine taking the same amount of money and building a scanning device the size of a 35mm negative. Now that's a quality scanner.
So what parts of a scanner are important? In my opinion, three items need the utmost of careful detail.
Optical Quality of the ScanThe optical quality refers to the natural optics and the ability of the scanner to turn an image into dots. Notice I said the ability of the scanner to create dots. Software interpolation, or turning a raw scan into dots through guesses in software, is best done outside of any actual scanning. Adobe photoshop has this ability and extensive research has been done on different methods for increasing picture sizes.
Instead, what is the raw scan? If the printing world uses 300 dpi (dots per inch) or 360 dpi, is that enough for a scan? My answer is: that is enough if you want prints the size of a 35mm negative. Scanning film this small and enlarging it to 13 x 19 inches is not difficult with the appropriate scan. My choice uses 4,000 dpi and creates a 45mb greyscale image or a 133mb rgb (red, green, blue) image. Note that the color image is three times the size of the greyscale image. This brings us to the second quality.
Quality of the Light SourceThe light source is what penetrates the film and gives the scanner something to record. Any color scanning must have the ability to scan the red, green and blue layers of the image. This not only provides better detail of the image, it provides three layers of the image file.
Most good photography image software uses these three layers to manipulate the image into it's final form. For example, the blue layer produces the most noise, or spots, in an image. Thus, the noise reduction is frequently carried out the strongest in the blue layers.
Today's advances in LED technology allow for precise light sources that consume little power and have incredible long lives. This is my preference over other bulb sources.
Quality of the Scanning GlassThe final critical item is the glass that passes the scanning light through to the sensor. I believe glass is still used to protect the sensor and keep dust and dirt away as well as provide a surface to keep the film flat.
However, cheap glass produces aberrations in the scan. Good quality glass has the same characteristics as a quality camera lens. The glass is not as expensive as a lens because it is flat and not curved, but that doesn't mean it remains cheap. What it does mean, is that your various color layers will be produces with minimal error to the quality of the negative or slide.
ConclusionChoosing a scanner is a lot like choosing a camera and lenses. We want the best quality for our money. This means choosing a scanner meant for film and photography. We didn't even discuss the important time savings for scanners that can load long strips of film or cartridges full of slides and scan unattended. These are features built into the best film scanners, so if you follow the rest of these guidelines, you will inherit the efficiency.
My scanner of choice is the Nikon Coolscan 5000 ED. This scanner fits the bill above and has a variety of attachments available for negatives and slides. However, there are other Nikon models available that allow for larger format negatives. I only shoot 35mm so the 5000 works well for me. Be prepared to spend some bucks, the 5000 costs about $1,000. However, remember this is the last line before you manipulate your image in a computer.
One of the other advantages of the Nikon scanners is the built-in Digitial ICE Technology. This technology along with others helps in reducing film grain effects and removing dust spots and scratches. This saves considerable post processing efforts. Unfortunately, this only works with color images.
Pick a quality scanner and you will end up with a quality digital image when put next to the original slide or negative.
Don't forget to visit my photography web site where we sell museum quality black and white prints framed to last up to 175 years - Outdoor Images Fine Art.